problem is when my computer switch on no beep sound coming and didn't detect the monitor but computer working properly.not displaying monitor
then i switch off the computer and switch on the beep sound is coming and detect the monitor and working properly.
why first time doesn't detect the monitor?

Your computer is probably setup so that when you hit the Power key, it goes into Hibernate mode.... Or, the Windows power settings are set to go into hibernate mode after an hour or whatever.

When a computer is in Hibernate mode, it looks like it is completely off. When you press the power button, it doesnt beep because it is not going to have to start up all the way from scratch. It just reapplies power to the system, reads the hard drive to figure out where it left off, and voila, you are in.

Some video cards don't like Hibernate... perhaps its the motherboard not giving the right initialization to the video card, so the computer looks like it "just turned on", without video.

You do "shutdown... turn off" to bring it down... then power it back on, and it works great.

Do you have kids or someone in the house that might just push the power button instead of properly shutting down? If they just hit the power button, and its set to Hibernate when the power button is pushed, that's your answer.

To find out, do the following:

1. Right Click on the desktop
2. Select "Properties"
3. Select the "Screen Saver" tab
4. Click the "Power" button
5. Select the "Advanced" tab
6. Under the "Power buttons" section, check out what options you have there. If either the power or sleep button are set to hibernate when pressed, that could be the problem.